Add macOS menu bar app with chat and settings

- Restructure project into three targets:
  - AppleIntelligenceCore: Shared gRPC service code
  - AppleIntelligenceServer: CLI server
  - AppleIntelligenceApp: Menu bar app

- Menu bar app features:
  - Toggle server on/off from menu bar
  - Chat window with streaming AI responses
  - Settings: host, port, API key, auto-start, launch at login
  - Proper window focus handling for menu bar apps

- Add build scripts for distribution:
  - build-app.sh: Creates signed .app bundle
  - create-dmg.sh: Creates distributable DMG

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Sources/AppleIntelligenceApp/Models/AppSettings.swift

@@ -0,0 +1,52 @@
+import Foundation
+import ServiceManagement
+
+@Observable
+final class AppSettings {
+    var host: String {
+        didSet { UserDefaults.standard.set(host, forKey: "grpc_host") }
+    }
+
+    var port: Int {
+        didSet { UserDefaults.standard.set(port, forKey: "grpc_port") }
+    }
+
+    var apiKey: String {
+        didSet { UserDefaults.standard.set(apiKey, forKey: "api_key") }
+    }
+
+    var autoStartServer: Bool {
+        didSet { UserDefaults.standard.set(autoStartServer, forKey: "auto_start_server") }
+    }
+
+    var launchAtLogin: Bool {
+        didSet {
+            do {
+                if launchAtLogin {
+                    try SMAppService.mainApp.register()
+                } else {
+                    try SMAppService.mainApp.unregister()
+                }
+            } catch {
+                print("Failed to update launch at login: \(error)")
+            }
+        }
+    }
+
+    init() {
+        self.host = UserDefaults.standard.string(forKey: "grpc_host") ?? "0.0.0.0"
+        let savedPort = UserDefaults.standard.integer(forKey: "grpc_port")
+        self.port = savedPort == 0 ? 50051 : savedPort
+        self.apiKey = UserDefaults.standard.string(forKey: "api_key") ?? ""
+        self.autoStartServer = UserDefaults.standard.bool(forKey: "auto_start_server")
+        self.launchAtLogin = SMAppService.mainApp.status == .enabled
+    }
+
+    func resetToDefaults() {
+        host = "0.0.0.0"
+        port = 50051
+        apiKey = ""
+        autoStartServer = false
+        launchAtLogin = false
+    }
+}

Sources/AppleIntelligenceApp/Models/ChatMessage.swift

@@ -0,0 +1,22 @@
+import Foundation
+
+struct ChatMessage: Identifiable, Equatable {
+    let id: UUID
+    let role: Role
+    var content: String
+    let timestamp: Date
+    var isStreaming: Bool
+
+    enum Role: Equatable {
+        case user
+        case assistant
+    }
+
+    init(role: Role, content: String, isStreaming: Bool = false) {
+        self.id = UUID()
+        self.role = role
+        self.content = content
+        self.timestamp = Date()
+        self.isStreaming = isStreaming
+    }
+}